Field of the Invention
The present invention relates to an optical fiber winding reel used to wind up an optical fiber such as an optical fiber for communication and relates to an optical fiber in a state being wound around the optical fiber winding reel, that is, a reel-wound optical fiber.
Description of the Related Art
As a reel (bobbin) used to wind up an optical fiber, a reel having flanges that are provided at both ends of a cylindrical winding body (main winding body which will be described later) is generally used.
Additionally, when shipping fiber products, generally, optical fiber products are shipped in a state where an optical fiber is wound around a reel, that is, in a configuration in which an optical fiber is wound around a reel.
However, for an optical fiber for communication, various measurements or inspection such as measurement of transmission loss for quality guarantee or the like are generally carried out in a state where the fiber is wound around a reel.
For this reason, regarding an optical fiber that has a long length and is in a state of being wound around a reel, it is necessary for both ends of the optical fiber to be exposed such that a length of the exposed portion is, for example, several meters to ten several meters.
Here, since the end portion (end edge) of the winding ended portion of the reel-wound optical fiber is located at the outermost layer of the winding body of the reel, the end portion can be easily exposed thereat.
However, in the case where the winding start portion (start end) of the optical fiber is simply wound around the winding body, the winding start portion is located at the innermost layer of the wound layers provided on the winding body on which the optical fiber is stacked and wound, and the winding start portion is buried in the wound layers.
Consequently, as a conventional optical fiber winding reel 10, as shown in FIG. 18 as an example, a reel 10 is known in which an auxiliary winding body 16 is provided on the outer side of the main flange 14A that is one (winding start side) of main flanges 14A and 14B located on both sides of a winding body 12 (main winding body), and a hole 18 that penetrates through both the inner face and the outer face of the main flange 14A is formed at the position of the main flange 14A which corresponds to the position near the outer peripheral face of the main winding body 12 (for example, refer to Japanese Unexamined Patent Application, First Publication No. 2001-322767).
When an optical fiber is wound using the reel 10 shown in FIG. 18, the winding start terminal of the optical fiber is inserted into the hole 18 of the main flange 14A from the inner face of the main flange 14A (surface near the main winding body 12), and the winding start terminal is drawn toward the outer face of the main flange 14A.
Furthermore, the optical fiber is drawn through the hole 18 of the main flange 14A so as to obtain a certain length thereof, the optical fiber is wound around the auxiliary winding body 16, and thereafter the optical fiber is wound around the main winding body 12.
However, in the case of using the reel 10 shown in FIG. 18, a user must manually carry out the operations (manual-handling task) of causing an optical fiber as fine as a hair to pass through a small hole 18, obtaining a certain length of the optical fiber by drawing the optical fiber, and winding the drawn fiber by the above-described manner around the auxiliary winding body 16.
Because of this, it has been extremely difficult for an initial operation of winding an optical fiber around the reel 10 to be mechanized or automated.
Consequently, it is difficult for the above-described winding operation to be carried out by total automation, and there is also a limit in promotion of streamlining the operation and reduction in cost.
On the other hand, as shown in FIG. 19, a reel 10 on which a slit 17 is formed on a main flange 14A located at the winding start end side thereof has conventionally used (for example, refer to Japanese Unexamined Patent Application, First Publication No. H9-120010, Japanese Unexamined Patent Application, First Publication No. H11-236171, or the like). The slit extends from the outer circumferential edge of the main flange 14A toward the inside thereof in the diametrical direction of the main flange 14A so as to reach a position on the outer peripheral face of the main winding body 12.
In the case of using the reel 10 shown in FIG. 19, firstly, a portion that is located at the winding start side of an optical fiber is wound around the auxiliary winding body 16, thereafter, the optical fiber passes through the slit 17 from the auxiliary winding body 16 and is introduced into the main winding body 12, and the optical fiber can be wound around the main winding body 12.
According to the above-described method, in an initial step of a winding start process, when the optical fiber is introduced into the main winding body 12 from the auxiliary winding body 16, it is only necessary to put the optical fiber into the inside of the slit 17 from the outside of the main flange 14A, the winding operation can be easily mechanized or automated.
For this reason, in order to optimize the winding operation step and realize total automation therefor, unlike the reel 10 shown in FIG. 18 is used, it is preferable to use the reel 10 having the main flange 14A shown in FIG. 19 on which the slit 17 is formed.
However, regarding the reel 10 having the main flange 14A shown in FIG. 19 on which the slit 17 is formed, there are problems as follows.
Particularly, in the reel having the slit 17 that extends in the diametrical direction of the main flange 14A so as to reach a position on the outer peripheral face of the main winding body 12, there is a problem in that the degree of strength or the degree of rigidity of the main flange 14A inevitably becomes lower than that in the case where the slit 17 is not formed.
Specifically, in the case of handling a product around which an optical fiber is wound (reel-wound optical fiber), in many cases, a user picks up the reel with their fingers of one hand, an optical fiber is loaded on a feeding device or a winding device such as various measurement devices, the optical fiber is removed from the aforementioned devices, or a product around which the optical fiber is wound is portably carried.
In this case, there is a significant problem in that the degree of rigidity of the main flange 14A becomes lower as a result of forming a slit to the main flange 14A.
This problem will be described in detail with reference to FIGS. 20 to 22.
For convenience of explanation and preparation of drawings, the reel 10 is shown in FIGS. 20 to 22 so that right and left positions shown in FIG. 19 are reversed, and a right main flange is represented by reference numeral 14A.
As shown in FIG. 20, in the case where the user picks up the reel 10 with their hand 30, in many cases, the user inserts a finger other than their the thumb 31 (for example, the index finger 32 and the middle finger 33) into a shaft hole 11 that opens at the center portion of the end face of the reel 10 (the hole is a portion that is used such that a rotation shaft of a winding device used to wind an optical fiber or a rotation shaft of a feeding device used to an optical fiber is inserted thereinto), the user puts their thumb 31 on the outer circumferential edge portion of the main flange 14A, and the reel 10 is picked by the user.
In addition, a rotation shaft of a feeding device or a winding device such as various measurement devices generally extends in a horizontal direction.
Because of this, when the reel 10 is loaded into the above-mentioned devices or when the reel 10 is removed from the above-mentioned devices, generally, it is necessary to hold the reel 10 so that the central axis line O of the reel is maintained in a horizontal position.
At this time, the point P (the position on the outer circumferential edge portion of the main flange 14A) on which the user puts their thumb 31 is separated from the position of the center of gravity G of the reel in the lateral direction thereof and is located at a position upwardly separated from the horizontal axis line O passing through the position of the center of gravity G.
Accordingly, as indicated by an arrow F, a force is applied to the point P in a direction perpendicular to a flange plate surface.
That is, the force F (force that causes the main flange to be bent outward) that causes the main flange 14A to be deformed outward is applied to the point P.
On the other hand, since the slit 17 is formed on the main flange 14A, at the position at which the slit 17 is provided, the continuity of the shape of the main flange 14A in the circumferential direction thereof is absent.
Therefore, the degree of strength or rigidity of the position near the slit 17 which resists against a force in a direction perpendicular to the flange plate surface is low.
Furthermore, in the case where the position P on which the user puts the aforementioned thumb is located close to the slit 17, there is a concern that the flange plate of the main flange 14A is deformed at the portion including the position P on which the user puts their thumb.
Particularly, as shown in FIGS. 21 and 22, the flange plate of the main flange 14A is bent outward at the portion including the position P on which the user puts their thumb (retroflexion).
In this case, a space S occurs near the slit 17 and between the surface 40a of the optical fiber layers 40 that are wound around the main winding body and the inner surface 14Aa of the main flange 14A.
Subsequently, since a winding tension is applied to the optical fiber when the optical fiber is wound around the reel, if the width of the space S is large, the optical fiber forming the optical fiber layers 40 is dropped into the space S, and the winding shape is deformed.
That is, since the winding tension includes a component of a force directed to the radial-inner direction of the flange plate, a force directed in the radial-inner direction of the flange plate is always applied to the optical fiber forming the optical fiber layers 40 in the reel-wound optical fiber.
Consequently, if a large space S occurs at the surface 40a of the optical fiber layers 40, the optical fiber is dropped into the space S by the above-mentioned force directed in the radial-inner direction of the flange plate.
Accordingly, an alignment state of the optical fiber layers 40 is deformed due to the above-described dropping of the optical fiber into the space S, and the winding shape is thereby deformed.
In the case where the above-described deformation of the winding shape occurs, it is difficult to smoothly draw the wound optical fiber. Furthermore, a lateral pressure is applied to the optical fiber by the deformation of the winding shape, a transmission loss occurs in the reel-wound optical fiber, and there is also a concern that characteristics of the optical fiber cannot be accurately measured in a state where the optical fiber is wound around the reel.
Therefore, as a result of making the degree of rigidity of the flange plate higher in advance by increasing the thickness of the main flange 14A, an occurrence of warpage of the flange plate near the slit 17 is prevented and the space S is not formed even in the case where the user holds the reel near the slit 17 as mentioned above. Because of this, it is possible to prevent the optical fiber from dropping into the space in the case where the user holds one side of the reel with their fingers in the above-described manner.
However, in the case of attempting to reliably prevent the flange plate from being bent near the slit, the thickness of the flange plate must be significantly thicker.
In this case, the weight of the reel increases, the handling ability of the reel is deteriorated, and furthermore, there is a problem in that the cost of the material used to form a reel increases.
Accordingly, it is desirable to prevent an occurrence of dropping of the optical fiber into the space S, which is due to bending of the flange plate when the user holds the reel as mentioned above, without an increase in a thickness of the flange plate.